Galvanizing process



E. L. WATROUS. GALVANIZING PROCESS. APPLICATION FILED OCT. 1. I917.

Patented Dec. 9, 1919.

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Specification of Letters Eatent.

Patented Dec. e, rte-re.

Application filed October \1, 1917. Serial No. 194,104.

To all whom it may concern:

Be it known that I, EDWARD L. WATROUS,

a citizen of the United States, residing at tion.

This invention relates to galvanizing processes and particularly to aprocess for simplifying and rendering more efiicient and cheaper thegalvanizing of small articles such as bolts, nails'or the like, althoughthe invention in its main features is also applicable to any formofgalvanizing. The ordinary process, of galvanizing consists in providinga vat of moltenj spelter into which the articles to be galvanized aredipped. It is necessary to cover the articles to be galvanized priortotheir being put into the molten spelter with a coat of sal ammoniac,muriate of zinc, or some other similar substance to act as a flux. Inthe commercial process of galvanizing heretofore carried out, a vat ofmolten spelter is provided upon the top of which floats a layer of theflux employed. The articles to be galvanizedare introduced into themolten spelter through the flux, picking up the coat of flux as theypass through this material. When the vat is charged, a portionof theflux' is skimmed ofi the top of the spelter and the coated articlesremoved from the spelter through theopenmg thus made.

This process is open to serious objections,

although it is the most eflicientv and simplest heretofore developed. Inthe -first place, the placing of the flux on top of'the rmalten speltercauses a very rapid evaporation, and a consequent high loss ofthe flux.Again the operation of skimming off the flux to make an opening throughwhich ,to withdraw the articles consumes considerable time and labor,and must be carefully done. Another objection to this process is thefact that the articles to be introduced into the spelter cold extractfrom the spelter, which has a comparatively low specific, heat, a largequantity of its heat, which, chills the spelter to such'a deg'reethatnotonly must the work be frequently interrupted to permit the spelter towarm up to the required temperature, but very; hard firi dered'necessary to keep 1 is rem" the operation going.

at all successfully, and the articles to be coated do not get a thin,uniform coat. This firing rapidly burns out the spelter vats, and, ofcourse, is expensive and requires additional labor.

Furthermore, it is obvious that under the process just described, thearticles must remain in the spelter until every part thereof has reachedthe temperature of the spelter, notwithstanding the. fact that certainparts of the articlemay long prior to that time have reached therequired temperature and received sufiicient coat. This again introducesthe time-consuming factor, and furthermore, is responsible forunsatisfactory galvanizing, because the longer the articles remain inthe spelter the heavierthe coat placed upon them, and if certain partsof the articles take longer to reach the required temperature than otherparts, the coat upon the articles will be uneven and upon the morerapidly coated parts there will be lumps or e'xcrescences of zinc. This,in addition 'to consuming a large amount of extra spelter, involving anextra expense, is furthermore objectionable because a thick coating orlump of spelter on any article is apt to chip or crack ofi', taking wlthit the superficial coat as Well, rendering the articles liable to rust,and furthermore, clogs the screw: threads and other fine points,rendering special machining necessary, in many instances after thearticles have been galvanized, which machining at some point or othergoes through the, coat of zinc, again introducing the. liability torust. The desideratum in galvanizing is a uniform completelycovering'the article but as thin as practicable, a very thin coat beingamply suflicient to prevent rust, and from all standpoints ,being themost satisfactory and the mostperfect, because most thoroughly united tothe article.

'The most valuable function of this invention is in 'treatin smallarticles like 'nails, tacks, screws, rlvets, washers, small otherwisethe flux would be burned off, oxi dation would take place and the workwould -not coat. This being the case the introduction of a mass ofcolder metal chills the zinc and it solidifies around the outside of themass, leaving the center untouched. The whole mass often rises andfloats on the surface, as cold zinc'is lighter than hot, thus exposingstill less surface to the heat. As the mass gradually warms up, the zincgradually melts and flows" into the center, but is constantly chilledand retarded as 1t meets new cold metal. The longer the work stays inthe bath, the heavier coat it takes on, so, that by the outside articleshave taken too heavy a coating and will be rough and scaly, while if thebasket is lifted as soon as the outside articles are ready, the centerwill still be black and uncoated.

Among-the objects of my invention, therefore, is to provide a processwhich wlll greatly increase the elficiency of galvanizlng small articlessuch as bolts, nails, or ,the like; 1

further to render the process of galvanizing cheaper and moresimpleyfurther to make possible the application of a thin, uniformcoating to the articles to be galvanized whereby they will besubstantially free from lumps of spelter or too thick a coating, thusreducin to the minimum the danger of portions 0? the coating chipp o'fland leaving the article llable to rust; also eliminating1 the danger oflumps of spelter the galvanizing;

threads in the case of clogging t e screw like, thus removing the bolts,screws, or,the

necessity of using spec al machinery to go over such threads aftergalvanizing; further to reduce the time necessary for the articles toremain in the in a much neater and smoother product of and such furtherobjects and advantages as-will later become more readily apparent.

y improved process is hereinafter -ex plained in connection with theannexed drawing,

view of a galvanizing tank for carrying out my process.

Fig. 2 shows an elevation partly broken of the galvanizing tank shown inFig. 1.

.Fig. 3 shows a vertical section ofa flux Fig. 4 shows an elevation of acentrifugal machine for removing excess material from galvanizcdarticles. My invention contemplates treating the articles to begalyanized by first covering them with a heavy coat ing them in flux Fin tank T, sal ammoniac being the most practicable, (however, I-may useother kinds of flux if desired,) and then drying them to such a remains.Any cons derable quantity of moisture would cause an explosion when thework is poured into the bath. The best 1 practice isto then heat thearticles coated the time the center is ready,

ing or cracking spelter; further to resultin which Figure 1 shows a planof fiux,.as by pl'ac it is hardly perceptible.

point that no moisture with flux to as high a degree as possible withoutdriving off the flux, although fair results may be obtained with workthat has been allowed to cool. after drying. A suitable empty basket ordipper B is then submerged in ,the zinc bath Z in galvanizing bath V andthe work on the surface of the zinc inside the basket. The particlesbeing well scattered, as by means of flaring spout S, no one of themexterts much chilling effect upon the zinc and each one will almostimmediately take the coating and sink. 2 Should too many of theparticles fall together and form a conglomerate, this will be small andthe operator can quickly slice it under the surface with a few strokesof the skimmer. As soon as the last article is under the surface, thesurface 'of the zinc should 'be quickly skimmed and the receptaclelifted and agitated, as by rotating or the like, to throw off thesurplus metal. One form of such agitating means is shown in my PatentNo. 1,221,397, granted April 3, 1917, as shown in elevation in Fig. 4 ofthe present draw- 1ng. 1

This may be varied by using a flux blanket on top of the kettle,lowering the empty basket through the flux andthen pouring the articlesto be galvanized into the basket through the flux blanket on the surfaceof the metal. In using this-method, it is not so necessary to have thework dry, and in fact, it may come from the pickling tank quite wet anddoes not need to be previously fiuxed.

The best results, however, will be obtained when the work has beenprefluxed and preheated. Of course, all these methods presume that thework has been previously cleaned, by pickling or other methods.

The main part of my invention, lies in thepouring or sprinkling of thework upon the surface of the metal thus scattering the articles to becoated instead of introducing them in a massl' By pouring? Imean vallowing the articles to escape slowly from a container and drop intothe galvanizing vat, substantially out of contact with each 0 er, sothat freezing is prevented. This may be directly from the container tothe vat or from the container to a spreading chute and thence to'thevat.

Articles treated by this method will take on a coat, which, whileheavystand several times the United States Governmen t test forgalvanization, is sosmooth enough to poured or sprinkled and clean anduniform that m measurement Nuts, may be turned upon bolts withoutrecutting' the threads, machined pieces will fit together without beingrecut, and in short, the finest possible results are obtained with aminimum cost for, spelter, labor, flux and fuel, so that the cost ofthis fine work is only restate "from one-half to one-third of that ofthe ordinary rough work.

Having now described my invention,

I clainit- 1. The process of galvanizing which consists in firstsubmerging in a bath of molten zinc an empty perforated basket or otherreceptacle and then sprinkling or pouring upon the surface of the zinc,inside the basket, the previously fluxed articles to be gal vanized,then removing the receptacle and the work contained therein andagitating the same to remove the surplus zinc.

2, The process of galvanizing, which consists of submerging in a bath ofmolten zinc a perforated basket or other receptacle, then covering thesurface of the zinc 'with a blanket of flux, then pouring or sprinklinginto the receptacle, through the flux, the articles to be galvanized,skimming ofi the flux, removing from the zinc bath the receptacle andthe work contained therein and agitating the same to remove the surpluszinc.

3. The process of galvanizing which consists in pouring or sprinklingthe articles to be coated upon the surface of a bath of molten zinc,-andpermitting the force of gravity to separate the articles which have beencoated from those which have nottaken a coat, whereby to cause the freshhot zinc to have access to the uncoated portions. v

4. The method of-galvanizing which consists in'scattering in asubstantially separated condition the articles to be coated, upon thesurface of a bath of molten zinc, permitting each article which has beencoated to sink as soon as it takes its coat, where' submerging a perorated basket in said bath,

the uncoated articles floating upon the surface of thebath will bereadily acces-- sible to the fresh hot metal of the bath and in turnquickly take their coat and sink..

5. The process of galvanizing which consists in submerging a perforatedreceptacle in a bath of molten zinc, coating with flux the articles tobe galvanized, sprinkling or scattering said articles upon the surfaceofthe zinc inside the receptacle, removing the receptacle with itscontents, and then removing the surplus coating from said articles bycentrifugal force.

6. The process of galvanizing which consists in providin a bath ofmolten zinc,

covering the surface of said zinc with a blanket of flux, pouring orsprinkling the articles to be coated into said basket and through theblanket of flux, removing the basket from said bath, and then removingthe surplus zinc from the articles in said basket by centrifugal force.

7. The process of galvanizing which consists in covering with a flux thearticles to be coated, and then heating said articles, pouring orsprinkling said articles into a perforated receptacle submerged in abath of molten zinc, removing the receptacle from said bath, andagitating said receptacle to remove the surplus zinc from said articlestherein.

8. The process of galvanizing which consists in providing a bath ofmolten zinc, submerging a perforated basket in said bath, covering thesurface of said zinc with. 'a blanket of flux, preheating the'articlesto be coated and then pouring or sprinkling them through the fluxblanket into the zinc in said basket, removing the basket from saidbath, and then removing the surplus zinc from the articles in saidbasket by centrifugal force.

9. The process of galvanizing, which consists of submerging in a bath ofmolten zinc a perforated basket or other receptacle, then covering thesurface of the zinc with a blanket of flux, then pouring or sprinklinginto the receptacle, through the flux, the articles to be galvanized,skimming ofi the flux, removing from the zinc the receptacle and thework contained therein, and sub:

jecting the same to centrifugal action to remove the surplus zinc.

10. That step in the pr ing which consists in sprinkling the articles tobe galvanized upon the molten galvanizing mass.

11. The improvement in the art of galvanizing which consists inscattering the articles to be galvanized upon the surface of the moltengalvanizing mass in a perforated container submerged in said galvanizmgmass.

In witnesswhereof, I hereunto subscribe my name to this specification inthe presence of two witnesses.

, EDWARD LAG-EY WATROUS. Witnesses:

F. H. Sammns, T. M. QUEBEDEAUK,

ocess of galvaniz-

